‘65 Triumph T120R Bobber - “Ticket To Ride”

doc_rot

Oh the usual... I bowl, I drive around...
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the heat shields are super slick. looks great.
 

3DogNate

"You Meet the Nicest People on a Honda"
LowBrow posted a picture of your bike on their FB page.
Yep, they asked permission first... Todd at Lowbrow had really good things to say when I chatted with him. Love the comments on their posts, the feedback is good.
 

3DogNate

"You Meet the Nicest People on a Honda"
My last (first decent) shake down ride exposed a few things I need to address. Otherwise the bike rides and handles wonderfully, the riding position is fantastic, transmission shifts perfectly.

1.) The motor is very tight and I'm building up excessive crank case pressure. A leak down test showed that I'm getting <5% loss which is a little less than is typical. The timed disk breather on this bike isn't venting enough pressure. I'm going to employ a racing trick (thanks to a great article from @grandpaul) and vent my crank case via the timing plug and a reed valve and a catch can. (waiting for parts)

2.) While functional, I don't like the 1>2 throttle cable setup. I'm switching to a dual cable throttle and individual cables. Need to switch to a different set of grips too, these Vans grips get dirty too easy. Switching to a set of white coke bottle grips. (done)

3.) WOT is a little lean - I'm going to add a set of pod filters in place of the tiny velocity stacks and see if that's enough to make WOT happy. If not I'll have to bump up my main jet a size. I'm modifying a set of POD filters by JB welding a set of filters to my velocity stacks to make a slick pair of screw on pods and not have to use ugly clamps, lathe work is done will glue 'em up later.

4.) I'm going to need to add a hose barb to the oil cap to add a hose to vent the oil tank a little better. I can't run much oil at all in the tank without it puking out the vent hole. (doing today)

5.) The speedometer is not liking the vibrations. I'm going to have to figure out a rubber mount to get rid of some vibes. Will try modifying my current mount with some grommets and spacers and see if that is enough to calm that thing down. (Low priority, after the other stuff)
 

Jimbonaut

Over 1,000 Posts
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Thanks for the reminder, need to rubber mount my speedo and tach too.

Buddy of mine has those Vans grips on his ride - I like 'em and they feel good too. Is it just because they're white they're getting dirty or the depth of the tread as well? The black ones would look sweet on your bike...
 

3DogNate

"You Meet the Nicest People on a Honda"
Thanks for the reminder, need to rubber mount my speedo and tach too.

Buddy of mine has those Vans grips on his ride - I like 'em and they feel good too. Is it just because they're white they're getting dirty or the depth of the tread as well? The black ones would look sweet on your bike...
They feel great... I'll use em again on something.... they are so squishy grippy that dirt just clings to it / in it and it's really hard to keep them clean. Grips are cheap... we'll see how the smooth coke bottles fair. I'll switch to black if they are no better.
 

teazer

Over 1,000 Posts
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Triumph changed the design to breathe through the primary chaincase. That way it has a larger volume to breathe into. That mod was pioneered by Boyer Racing IIRC. They added a breather outlet to the inner face of the chain case at the top.

Ducati uses a reed valve on their crankcases and on the race bikes they make the catch tank larger and on some models put a reed valve inside the airbox. The key is not so much the reed valve but the extra volume to allow the oil to separate out and drain back into the motor.
 

3DogNate

"You Meet the Nicest People on a Honda"
Triumph changed the design to breathe through the primary chaincase. That way it has a larger volume to breathe into. That mod was pioneered by Boyer Racing IIRC. They added a breather outlet to the inner face of the chain case at the top.

Ducati uses a reed valve on their crankcases and on the race bikes they make the catch tank larger and on some models put a reed valve inside the airbox. The key is not so much the reed valve but the extra volume to allow the oil to separate out and drain back into the motor.
My engine is a '65 and I'm running my primary dry with a belt drive. So no shared oil between primary and crankcase like the '70+ bikes. I'm trying to decide what to do with the stock breather tube. Do I just plug the hose and have the timing plug vent as the one and only vent? I am thinking that I certainly should not tie them together without a second reed valve to ensure that there's not dueling vents happening. I'm thinking it needs to get plugged.
 

teazer

Over 1,000 Posts
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I didn't notice the belt drive. That makes a difference.

I personally wouldn't worry too much about the reed valve. There was a movement a few years ago with cars to run vacuum pumps on the crankcases to hold oil in and supposedly make more power. I'd be surprised if the difference was measurable on a 40hp motor. I can't remember what we did to our 62 Classic Racer (pre-unit) but I think we went with a larger bore breather straight out of the timing cover IIRC and the breather tube was large bore and went to the back of the rear fender, so it had some volume to dampen out pressure waves and allow any oil to condense out and dribble back.

In terms of one or both, the air flow would probably be easier to change with one pipe rather than two. That way if it leaked or smoked, there's only one pipe to change ad not worry about which was the source of the pressure. With two pistons rising and falling together, there's a lot of crankcase volume/pressure changes to manage.

If that reed valve solution has been proven and you want to try it, I'd block off the timed breather for now and see how that works.
 

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